Usually the housing of a teleprinter is provided with a dial switch similar to the rotary dial of a telephone apparatus. The dial switch produces the selection pulses by rhythmically opening and closing a contact. The selection pulses are then conducted by way of a switching device and a teleprinter line to an exchange system. A dial switch of this type, however, has the disadvantage that it contains mechanically moving components which are subject to wear and which thereby may cause errors in the selection pulses being emitted.